Chronic low back pain (CLBP) is the single leading cause of disability worldwide. Like other forms of chronic pain, CLBP is believed to be associated with disruptions of normal patterns of brain activity in regions associated with sensory processing, such as the somatosensory cortex. Among these patterns are alpha oscillations, waves of electrical activity that arise from the collective firing of many brain cells. These and other patterns can be identified using common noninvasive brain imaging techniques. Researchers at the University of North Carolina investigated the relationship between alpha oscillations and chronic pain in 20 patients, along with possible therapeutic benefits of transcranial alternating current stimulation (tACS), a noninvasive technique that targets specific patterns within brain regions using electrical stimulation. The researchers hypothesized that restoring the electrical activity to normal levels in the brains of patients suffering from CLBP may reduce the severity of pain.

The study began by recording the strength of these “alpha oscillations” in a brain region involved in processing pain. They concluded that individuals reporting higher levels of chronic pain showed weaker alpha oscillations, implying their brain cells may not be working together properly. Each patient was administered a 40-minute session of tACS targeted to mimic the electrical properties of alpha oscillations and a separate session which served as a control. The order of treatments was randomized between patients (so some received the control first, and others the tACS first, but were not informed which), and the electrical activity and pain reporting were recorded after each session, which were separated by two weeks. The treatment successfully increased oscillations, and patients reported a lower pain after the tACS session.

While the reported difference in pain before and after the tACS session was only significant for one of the rating scales, a normal therapeutic paradigm would include multiple sessions. Thus, tACS must be further investigated as a long-term treatment for CLBP, along with its ability to target different patterns and brain regions, and to generalize to other forms of chronic pain. Even so, discovering that weaker alpha oscillations are associated with more severe pain in CLBP, and that targeting them can provide a potential therapeutic benefit, is a step forward in understanding and treating several chronic pain disorders. This also provides an avenue for researchers to investigate the connection between weaker collective activity among brain cells and dysfunctional sensory processing. The potential for individualized treatment depending on the patient’s specific brain activity may also improve results.

Thank you for the interesting article and the thought provoking comment about our study. What was unique here is that we selectively increased alpha oscillations in the motor/touch/pain areas where the pain is encoded. We have a new paper coming up that you will like since we have now investigated if autonomic tone changed by stimulation versus placebo. Stay tuned! Flavio